Imagine today is your 64th birthday and you decide to retire as of tomorrow morning. you have an annuity that pays you $80,000 per year for as long as you live after retirement, but the payments are not adjusted upward each year to reflect any inflation. if inflation can be expected to average 6% per year, use the rule of 72 to determine how old you will be when the purchasing power of your annuity will have been cut in half,, that is, to the equivalent of only $40,000 today: